Reversible pump controlled hydraulic cylinder system



Filed March 12, 1945 G. H. 'IIUIFIF'ERIDy REVERSIBLE PUMP CONTROLLEDHYDRAULIC CYLINDER SYSTEM a sheets-snm l www @MD ifg, Q. H. Humm@REVERSIBLE PUMP CONTROLLEU HYDRAULIC CYLINDER SYSTEM Filed March 12,1945 3 SheatB-Sheat 2 y 11W/Ewan E H- HUFFE/ED @wfg M9 Bm G. H. HUFFERD2944994@ REVERSIBLE PUMP CONTROLLED HYDRAULIC CYLINDER SYSTEM FiledMarch l2, 1945 X S Sheets-Sheet 3 f WM A TTOIP/VEYS Patented Sept. 14,"1948 REVERSIBLE PUMP CONTROLLED HYDRAULIC CYLINDER SYSTEM George H.Huierd, Shaker Heights, Ohio. as-

slgnor to The Weatherhead Company, Cleveland, Ohio, a corporatloApplication March 12, 1945, serial No. 582,317

'My invention relates 'to hydraulic apparatusv and concerns particularlyhydraulic operators useful i'or actuating any one of many mechanicaldevices-dependent for their operatlonon reciprocating motion.

A/general object of .my invention is to provide a hydraulic operatingsystem and method obviatlng the necessity for a fluid pressure supplyfrom a central point under considerable pressure. In this connectionitis an object of my invention to eliminate a hazard of rupture ofsupply piping from such a central source. whether such rupture takesplace by accident, wear and tear, or4 by destructive intent as in thecase of apparatus subject to enemy shell iire.

An object of the invention is to provide an arrangement with means foreffecting operation by reciprocating a rod hydraulically and with meansfor varrestingiand holding or locking the rod in any desired limiting orintermediate position.

A further object is to provide a hydraulic operator arrangement for usewhere great reliability is required. such as in aviation construction,for example. where members such as rudders, ailerons. elevators, landinggear and the like may be controlled by hydraulic pistons and rods.

I The utility ci the invention is not limited to the foregoingexamples,` and generally speaking it is an object of my invention toprovide a-hydraullc operator or method of operation for any 3o suitableneed where fluid pressure supply is generated at the point ofapplication only, and its use is controlled from a remote point withlitt-le likelihoodof interference or interruption.

A further object is to provide means for selectively actuating ahydraulic operator in either direction of reciprocation without relianceupon manually or mechanically operated supply valves.v

' Still vanother object of my invention is the pro- -vision ofelectricalmeans for actuating a hydraulic operator in either directionof'reciprocation and from a remote position. Thus an ob' 'ject is the.provision of an electrohydraulic operato'r.

More specifically an object of, my invention is to provide means forarresting and locking an operator in an adjusted position intermediatethe endsV of its travel, as well as at the ends of its travel, and toprovide for subsequent reciprocation off the operator in eitherdirection from such ana intermediate position. y

A further object of my invention is to maintain pressure fluid ina'closed circuit including a' cylinder having a piston therein securedto a rod extending through one end of the cylinder,

n of Ohio 6' Claims. (Cl. 60-52) and to take up the difference in volumeof the two ends of the cylinder due to the inclusion oi the rod in oneend.

Still another object of the invention is to provide a rugged and durablemechanism which may be subjected to severe operating conditions withoutdamage and which is economically manuiactured and easily assembled andserviced.

Other and further objects, features and ad` L vantages will becomeapparent as the description proceeds.

In carrying out the invention in a preferred form thereoff I provide acasing containing a cylinder and piston and having a preferablyreversible fluid pump mounted preferably upon the casing and directlydriven by a preferably reversible electric motor. A rod to be operatedis connected to the piston and :iiuid conductingpiping from the pump isconnected to the opposite ends of the cylinder for moving the piston inone direction or vthe other according to which end oi' the cylinder isconnected to the higher pressure side of the pump. Preferably valvemeans operated by the uid pressure are provided for selectivelyconnecting the high pressure side of the pump to either fluid-conductingpiping.

A better understanding of the invention will be afforded by thefollowing detail description considered in conjunctionvwith Vtheaccompanying drawings and its scope will be set forth in the claims. j n

In these drawings- Fig. 1 is a side elevation partly in section of myimproved electro-hydraulic operator for rods and the like; Fig. 2 is anenlarged longitudinal section of a portion of the apparatus of Fig. 1, aportion of the pressure bag and the partition supporting certainconduits being shown in elevation;

Fig. 3 is a transverse section of the accumulator or reservoir taken onthe line 3 -3 of Fig.. 2;'

Fig. 4 is a transverse section of the actuating mechanism in lookingposition taken on the line il--l of Fig. 2;

Fig. 5 is a similar transverse section showing the mechanism in positionto advance the rod, and Fig, 6 is a similar transverse section lshowingthe mechanism in position to retract the rod.

Like reference` characters are utilized throughout the drawing todesignate like parts.

For illustrating the invention, there is shown `in Fig. 1 anembcdimentof the invention taking .means may take the form of a tube 34,and channels to be pointed out hereinafter in connection witha'description of the specific details of the apparatus. Suitable valvessuch as poppet ,valves 4I, 48, 8i and B1 are provided for selectivelycontrolling admission of uid from the outlet or high pressure side ofthe pump to either end of the cylinder and these valves are adapted tobe operated by the fluid pressure of the pumpas will be explained morein detail hereinafter.

To facilitate manufacture, the structure shown in Fig. 1 is preferablyproduced by fabricating a number of separate parts and assembling them.A casing 8 may be provided for carrying the other parts of thestructure. To formthepiston receiving cylinder, a cylindrical shell`2i,Isealed by shoulder by the inner end of the cylindrical shell ture 24 forl rod 25 secured to thepiston 21. For

connecting the piston rod 25 to any suitable mechanical element which isto be operated, an at- \taching eyebolt 28 may be provided. As shown onFig. 2, a piston ring or packing 28 is preferably provided for thepiston 21, which is fully reciprocable in the hydraulic cylinder 2 I.

In order to avoid starvingthe gear pump. a

reservoir chamber or accumulator v28`for hy- I draulic uid is preferablyprovided in the casing 8 back of the cylinder 21 and separated from thelatter by a partition 30. vThe casing 8 is so formed that the partition30 is held against `a 2l and the same packing or gasket 22 seals boththe partition 30 and the cylinder. For the sake of compensating forvariations in quantity of uid temporarily stored in the accumulator 28,a gas bag .3l of flexible material, preferably elastic such as rubber isprovided. The bag 3i is adapted to occupy the greater portion oi' thechamber 28 and is filled with gas so as to expand or contract withvariations in pressure of the fluid pumped into the chamber 28 aroundthe bag.

gasket 22, may be threaded onto the casing 8 at v 'Means are providedfor enabling one of the pump ports 28 to be connected to the far endofthe cylinder 2I. For example, a passageway --32 .may be formed in thecylinder head 23 and I may provide a `fitting 33, a tube 34 connected totheY passageway 32 by the tting 33 and a fitting 35,- connecting thetube 34 to a passageway 38 in the casing 8.

As already pointed out, valves 4I, 48, 8l and 81 are provided forcontrolling the pump conary support (not shown).v The motor II ispreferably bolted to one end of the casing 8 for compactness ofassembly.

The motor il is preferably a relatively high speed motor, for example,one operating at approximately 5800 R. P. M. full load speed. Forcausing the motor II to run in either direction or remain at astandstill, a suitable reversing controller 1, which may be mounted at adistance, is provided having forward, reverse and standstill positions ER, and N, respectively.V It will be understood that such controllersinclude connections for reversing the absolute or the relativepolarities of the electrical energy in some part of the motor II. j'

In order to form a iluid pump reversible indirection of ow with reversalin direction otrotation of the motor I i, a rotary' type of pump-such asa gear' pump is preferably employed. Both the motor and the pump aremade a pa'rtxof` a unitary structure and the assembly is as compact aspossible to minimize the number of hydraulic lines, avoid moving pipejoints and provide arnaximum degree of reliability. To this end apaciyr-v pressure ports I9 and 20 are provided for the gear pump, one orthe other being the outlet port, depending upon the direction in whichthe pump gears are rotated. 4

The cylinder head2! is provided with an apernections to the cylinder 2l.Chambers for such valves are formed inthe casing. Thus there are twoaligned valve chambers 38 and 43 extending across the casing below thepassageway 38 above the gear pump and two aligned valve chambers 51 and53', below the'gear pump. A

connecting opening 31 is provided between the chambers 38 and 43, andthe chamber 38 is open to the passageway 38 from the pipe 34. Theintermediate connecting opening 31, in turn, is open to the `pump port20. The end of the chamber il adjacent the connecting opening 31 forms avalve seat and the opposite or outer end is closed by means of a screwplug 39 and a gasket 48.

The valve 4i slides freely longitudinally in the chamber 38. The valvehas a conical head and grooved sides and is intended to seat against theend opening of the chamber 38. The rear of the valve is provided with astem 42 which is sur-- rounded by a`coiled compression spring 43. Thisspring tends to hold the valve upon its seat and the extent oi. themaximum opening is deter-` mined by the spacing between the end of thestem 42 and the screw plug 33.

The second aligned lchamber has a bore 43 leading oii from theconnecting opening 31. Ad-

jacent the bore 43 is a larger bore 44. A removable valve seat 45 fitsin the larger bore against the shoulder formed by the smaller bore. Itforms a seat for the valve member 48 and has a peripheral groove 48connected at one point to the central bore of the valve seat 4B as shownin Fig. 4.

The large bore 44 of this chamber is closed by a gasketed hollow screwplug 41 which ts against the valve seat 45. The valve 48 in the smallbore 43 has a conical head fitting against the valve seat 45. The valvehas grooved sides to allow the fluid to pass in either direction. Acompression spring 48 holds the valve against its seat. `The rear ofthevalve has a shifting pin or stein'll,

, This extends through the connecting opening 51 and when the valve 48is open the stem 55 contacts the end of valve tl and opens the latter.

In the hollow screw plug d1 there is a chamber 52 vented as indicatedinto the large bore tit. The hollow screw plug forms a chamber in whicha free piston 55 is adapted `to reciprocate. This piston has a valveshifting pin t. projecting through the valve seat i5 and operatingagainst the head of -valve 455. A pipe 55 in the casing connects thechamber 29 with the peripheral groove t5 and thus provides communicationbetween the reservoir and the central space in the valve seat 45. Theposition oi pipe 55 is indicated on Figs. 4-6, and the end of the pipecan be seen inFig. 3 which is a section through the reservoir chamber2t.

The second pair oi' valve chambers is disposed in alignment across thecasing below the gear pump and parallel to the first pair of chambers.These latter valve chambers have a connecting passageway 55 which islikewise at the lower end of the pump tube l5. One of these valvechambers 51 is closed by the gasketed screw plug 55 at its outer end. Aport 55 and passage way extend from this chamber entirely through thereservoir '25 and the partition tu and open into the hydraulic cylinderbach of the piston 2li. A small passageway 5d connects the large bore ttwith chamber 5l.

A `valve oi with a conical head reciprocates in chamber 51 andris seatedagainst the opening 5B. The valve 5iy has a rear stem 52 which limitsits retraction against the screw plug 53. A compression coil spring 63serves to hold the valve normally closed.

`The fourth valve chamber in alignment with chamber 51 is shown to havea small Ibore 53 connecting-with thepassageway 55. The small bore leadsinto a large bore 54. The latter contains an annular valve seat member55 resting against the shoulder of the small bore. A peripheral groove66 ls provided for the valve seat and is connected at onepoint to the'central Space inthe valve seat. The valve 51 slides in the small boreand is seated against the annular valve seat 65. There is a coilcompression spring 58 back of the valve 61 and surrounding a valveshitting pin 59. The latter extends through the passage way 56 andoperates against the end of valve 5|.

A pipe leads from the peripheral groove 55 into the reservoir `25. Thispipe as well as pipe 55 extend well into the reservoir so as to supportthe gas bag 3l and prevent the latter from blocking their ends.

\ mechanism for reciprocating motion.- The` device is economicallymanufactured and easily assembled and serviced. It is rugged and durableand may -be subjected to severe operating condi- 4 tions without damage.

In the locked position as shown in Fig. d and when there is no lbackpressure in either direc',- tion, the liquid is in balance on both sidesot the .piston 21. The reservoir ports 55 and 59 are both open. Valve tlis closed bythe springtt. There being no back pressure there is no `eectthrough passagewayst, it, and '1i on the 'unloading pistoni@ in thelower valve. Consequently valves 51 and 5i are heid closed by springs 85and 53. Valve tu is closed by spring t9 as there is no back pressurethrough passageway 59. rIfhe valve 5l is closed by the spring 63 therebeing no back pressure from the reservoir 29 through pipe 1li. There isthus no effect on the unloading plunger fill.

In the event thereis back pressure exerted through pipe 55 from behindworking piston 2l. then this pressure is applied against the back ofvalve 5i without effect on it. The pressure also works throughpassageway .lil and back of free piston 53 to unseat valves I8 and tl.'In the absence of pump action'this can serve .only to connect thereservoir :29 through the pipe li5'to the I iront of the piston 21 byway of pipe 54. This may transfer duid to the forward side of theworking piston 21 but will not be su'illcient to add materially toitsbackward pressure.

A passageway 1| connects the large bore 54 with'the chamber 38 of thevalve ilrst above described. The large bore 64 is closed by means of ahollow screw plug 12. This forms a vented `chamber 13. The chamberslidably carries a free piston 14 which has a central valve shift pin15. The latter projects through the annular valve seat 65 and operatesagainst the face of the valve 51. Y

It will be evident that by the above described construction thehydraulic operating circuit can be restricted to the immediatevvicinityof the reciprocating mechanism. The. hydraulic means can be directed oroperated in either direction or can be locked in any desired limiting orintermediate position solely by reversing the flow of electric currentto a winding of the motor or by stopping this ilow when the desiredtravel has oc'- curred. Consequently the arrangement serves the primepurpose of providing the advantages of When back pressure occurs from infront of the working piston 21, then it is transmitted through pipe 34and against closed valve 4| .without effect. Some pressure is thenapplied through 'Il to unseat valves 51 and 5L The former thus connectsthe reservoir 29 to the near side of working piston 21 through pipe 59.Again no material effect will modify the back pressure on the oppositeside of the working piston 21.

Assuming the working piston isbalanoed then in order to advance theoperating rod 25 the pumpV must vrotate upwardly. outwardly/. anddownwardly drawing liquid from the upper port and opening valve 6|against its spring. Liquid pressure delivered around pistol/15| isdischarged through 59 tothe cylinder back ofthe piston 21 and causes thelatter to advance. At the same time the liquid pressure travelling upthrough pasageway 50 builds up pressureagainst free piston 53 and opensvalve I8 to permit discharge from pipe 55 to supply the pump. Pin 515Jopens valve 4l to allow liquid to return through pipe 34 and thus supplythepump.

In this operation the 'fourth or lower right hand valve in Fig. 4 isinactive.

As soon as the pumping is suspended, pressure back'of theoperatingplstonsis relieved and the valves return by spring operation to'their closed position.

In the retrac'ting-movement the pump operates in the reverse direction,namely, downwardly through the center. out and upward. Pressure is thusdelivered to valve 4i compressing the spring 43 and delivering liquidunder pressure through 54 to the front of piston 26 thus retracting thelatter.

" held valves.

Y through check valves and valve unloaders,

7 The pressure delivered through valve Il also traverses passageway Ilwhich operates the unloading or shifting piston 14 so that valve l1 israised from its seat. Excess liquid is delivered through pipe 'Ill tothe reservoir .compressingthe- 5 gas bag. At the same time pin 89' opensvalve Il and allows the liquid to discharge through passageway. from inback of the piston 21 to Y the passageway 1U and the reservoir 28; Assoonl retract the-piston.

The back-pressure occurring in pipe 59 would normally open valve 4I (bypressure through passageways 5l and 60 acting upon elements il, 5l, 48,50 andll).

This would 'merely anticipate the delivery of the pressure uid from thepump through valve Il and pipe 3l to the l front of the working piston21 and thus effect its retraction.

' In summary-the arrangement above described v utilizes the advantageoushydraulic operating mechanism for a reciprocating member and at the sametime insuresl this hydraulic system against undue risk of damage throughthe use of extendedplping. This result is accomplished by providing anelectric control circuit which operates `a reversible electric motordirect-connected to the fluid-pressure pump adjacent the piston cylinderof the operating rod.

Furthermore the arrangement is such that the.

. tate the draught of iluid both from the leading sld of the main pistonandv from the accumulator.

4 T he arrangement utilizes apressure pump which works; in eitherdirection to i'orce duid to the power cylinder through 'one of twospring These valves prevent reverse flow. The valves are mechanicallyunseated by pressure exerted .from the opposite side of the pump Onevalve and a Vcorresponding check valve cooperate in each direction ofpumping to supply the pump while in the opposite directionthey operateindependently to deliver high-pressure fluid to the powercylinder butVprevent its escape to the accumulator. 1

Having thus described my invention so that others' skilled in the artmay be able to under- Y stand and practice'the samel I state that whatthe piston, a reversible fiuld pump mounted adjacent the cylinder, fluidconducting piping from the pump to opposite ends of the cylinder, springbig/h pressure side of the pump to either fluid conducting piping, anaccumulator chamber in the casing and having passages connected to bothsides of the pump, a spring held check valve in each passage. a freepiston operable ,by pressure from the opposite side of the pump to openeach g check valve, and means on each check valve to open thecorresponding powervalve.

2.v In combination, a casing having a cylinder, a piston reciprocabletherein, a rod operated by the piston. a reversible iluid pump mounteda'djacent the cylinder, duid conducting piping from the pump to oppositeends of the cylinder, spring held power valves for selectivelyconnecting the high-pressure side of the pump to either fluidconductingpiping, an accumulator chamber in the casing and having passagesconnected to both sides of the pump, a spring-held check valve in eachpassage and aligned with a power valve, a free piston also aligned withsaid two first named valves and operable by pressure from the oppositeside of the pump, means on the free piston to open the check valve, andmeans on the check valve to open said power valve.

3. In combination, a casing .having a cylinder, a 'piston reciprocabletherein', a' rod operated by lthe piston, a reversible fluid pumpmounted adiacent the cylinder, fluid conducting piping from the pump toopposite ends of the cylinder, springheld power valves for selectivelyconnecting the high-pressure side of the pump to either iluidconductingpiping, an accumulator chamber in the casing and having passagesconnected to both sides of the pump, a spring-held check valve in eachpassage, a free piston operable by pressure from the opposite `side ofthe pump to open' each check valve, means 'on each check valve to openthe ,corresponding power valve, and a compressible element in theaccumulator chamber.v 4

4. In combination a pairV of cylinders, a piston portion in eachcylinder, a reversible pump, v

uid conduits between the pump and each cyllnder, spring held powervalves for selectively connecting the high pressurev side of the pump to,either cylinder, a reservoir, means connecting said reservoir to bothsides of said pump, a check valve in each of said connecting means, afree piston operable by pressure Yfrom the opposite side of the pump toopen each check valve, and means on each check valve to open anassociated power valve. l

5. In combination a pair of cylinders, a piston portion in eachcylinder, a reversible pump, uid conduits between the pump and eachcylinder, spring held power valves 'for selectively connecting the highpressure side of the pump to either cylinder, a reservoir, meansconnecting said reservoir to both sides of said pump.- s. spring heldcheck valve in each of said connecting means and alignedY with a powervalve, a. free piston aligned with each pair of said first two valvesand oper.- able by pressure from the opposite side of the pump, means oneach free piston to open its asso- 'elated check valve, and means oneach check valve to open an associated powervalve.

6. In combination a pair of cylinders, a piston portion in eachcylinder, a reversible pump, iluid conduits between' the pump and eachcylinder,

held power valves for selectively connecting the t r amsn compressibleelement 'in the accumulator chml Number ber. y 1,616,841 GEORGE H.HUFFERD.. 1,690,181 1,940,668 REFERENCES CITED 5 2,368,659 `The'following references are of record in the 111e 61' this patent: N b

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